Tolerance to diethylcarbamazine-medicated salt in individuals infected with Onchocerca volvulus

The tolerance of Onchocerca volvulus-infected individuals to diethylcarbama zine (DEC)-medicated salt (0.33% w/w) was assessed in 1996 in Tanzania in a double-blind placebo-controlled hospital-based trial involving 4 groups, e ach of 10 adult males. Groups I and II had O. volvulus microfilariae (mf) o nly, group III had both O. volvulus and Wuchereria bancrofti mf, and group IV had W. bancrofti mf only. Groups I, III and TV received DEC-medicated sa lt, whereas group II was a control to group I and received normal cooking s alt. Medication was given for 10 days. The mast pronounced adverse reaction s in groups I and III were mild-to-moderate itching and rash, beginning aft er 3-4 days and lasting for the remaining medication period. The reactions did not interfere with normal daily activities. By 20 days after the end of medication, adverse reactions had disappeared in all individuals. The low daily dose of DEC had no significant effect on the O. volvulus pre-medicati on mf geometric mean intensities (GMIs). In contrast, the medication signif icantly reduced the pre-medication W. bancrofti mf GMIs. The prospects for using DEC-medicated salt for control of bancroftian filariasis in areas whe re incidental infections with O. volvulus occur an discussed.